Light emitting diodes (“LEDs”) are commonly used as light sources in various applications. LEDs are more energy-efficient than traditional light sources, providing much higher energy conversion efficiency than incandescent lamps and fluorescent light, for example. Furthermore, LEDs radiate less heat into illuminated regions and afford a greater breadth of control over brightness, emission color and spectrum than traditional light sources. These characteristics make LEDs an excellent choice for various lighting applications ranging from indoor illumination to flash photography.
Flash photography applications require LEDs to be used in conjunction with specialized optics for focusing light that is output from the LEDs. Such optics needs to meet various design constrains. For example, it needs to be sufficiently small to fit in small form-factor photographic devices, such as smartphones and miniature cameras. Furthermore, it needs to collimate light well in the direction of the subject that is being photographed, while also providing a highly uniform light output when multiple LEDs are used as a light source.
Accordingly, the need exists for improved optical designs that meet the above design-constraints.